Spark Gap
According to the datasheet of many devices, spark gap is supposed to be placed across one AC input and the positive output rail. I've seen two spark gaps used on top and bottom side of certain reference designs. How these are connected, and when you have a dual output design, where and how to place spark gaps?
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Hi caroltech,
Spark gaps are best placed across the output positive and/or return terminals and one of
the AC inputs. The optimal placement and connection of the spark gap will also depend on the board layout.
For a dual output design, if the outputs have the same return, placing one spark gap across it and the AC input should be sufficient. You can also refer to the RDR-611 which is a 10 W dual output design.
For DER-535, the design underwent a series of evaluation and testing that considers ESD immunity and surge protection. This means that the current layout is able to protect the power supply from these events. While placing a spark gap across the output positive and the ac input is generally a better solution for most designs, doing this would mean that the new design must be tested for surge protection and ESD immunity.
Thank you for using PI Forum.
Thank you very much for the helpful reply. Everything is clear now!
Could someone please explain why the spark gap is connected between one AC input and the source of the MOSFET in the attached RD picture, and not the positive output rail, as suggested by the datasheet.